There were times with Rose, even she couldn't fix him. Times where the darkness overcame him and that smile didn't go back to normal for days. Times he only smiled to her and only acknowledged her on any planet they were on, Rose would have to ask him even if the other person was standing in front of them. He'd tell her and she'd tell them, she knew these moods and what set them off. She knew being anywhere near danger set him off in this protective mood. She wasn't scared of it, no, but he was.
She saw it but he felt it.
The Doctor couldn't help to bubble with anger as Rose's face was taken, when her mind was taken over by Cassandra, when they were stuck on Krop Tor, or when gas masked children threatened to make her one of them. All those times, and many more times, he had wanted to break apart the universe to get her back. The rage she saw, the sadness and the sorrow was nothing compared to what built inside him, day after day, trip after trip. Because one day he knew, that she wouldn't come back. She would be gone. And he always thought "today is the day I lose her" when these things happened, when she became yet another victim in his complicated and dangerous lifestyle.
One of the first time's he could have lost her, back on London with the Slitheen, he had a choice. To take the risk of losing her and save the world, or keep her. In the end he chose to save everyone, after making sure she'd be safe. That was when the initial panic began to sink in, even when they were faced with death before, it only dawned on him then she could be gone so easily.
And she was gone easily. Because today was the day, the day the Doctor lost his world in the matter of seconds. The day the Doctor lugged himself back to the TARDIS hopelessly and cried for hours on end on her bed, snuggling with her blanket that still smelled like her. The day the Doctor screamed at a TARDIS manual and threw it into a supernova because it said he couldn't get back together. The day the Doctor had destroyed multiple stars simply because he needed his anger to be released. He didn't check if they were supporting some small planet or life system no- he just blew them up and burnt them out as if they were a candle. It didn't matter, she was gone.
Facing her on that beach those days later. Not even a hundred hours without her and he was already going mad with grief and anger, he had to play calm. Sad and calm, but he wasn't calm- he wanted to rip the world apart and he would if he knew she would be fine, but she could die if the universes started to collapse again. Even seeing her made him feel better, hearing her voice even though she wasn't really there. There wasn't a beach or her pink cheeks and crying eyes, a sobbing voice that choked out I love you before he faded away.
When Donna had landed in the TARDIS he just wanted to get rid of her, especially when they were at the wedding and he saw that blonde being dipped down by a tall man in a suit. All he saw was Rose, Rose and him and their "hello"'s after Cassandra had left their bodies. When he flooded the tunnel he had every intention to go with it because what was the point? There was no Rose, no pink and yellow human who would run out and hug him when he got back into that god forsaken blue box of his. No hugs or kisses from her, or the smiles that made him melt inside. No- that was gone. All gone. If it wasn't for Donna he'd be dead, but he wasn't sure he cared.
Martha was great, he had mistreated her though. That whole year they were together and all he went on about was Rose and how she was godly and perfect- she was of course, but a girl who fancied him didn't want to hear that. So it wasn't much of a surprise when he had lost her too.
Donna came back- oh that was brilliant. Investigating all on her own, searching for that same blue box every day in and out because she wanted to travel with him now. She made him smile, truly laugh and smile despite Rose, despite it all. His best friend, but in the end she had to forget, and he lost her too. He became just another bloke, John Smith he had told her. Another bloke she could never see again for his fear of her remembering. That killed him too. But even then it all lead back to Rose.
His clone, as soon as he'd seen him, he was amazed. He was happy there were two of him now, double to mind power so he could get adventures done twice as fast. No one expected two Doctors. But as he realized, saw he was human, he realized- even with his Rose in his hand- what he needed to do. He needed to give him up to her, leave her again on that god forsaken beach. Never getting to tell her, never completing that sentence and having the other him win the kiss and the girl as he sauntered away into that old machine. The only thing that never left him. He never did get a proper goodbye, a bittersweet ending he supposed. Just bitter for him though, just bitter for him.
When he collected his reward of course he visited her last, and he smiled again. Smiled at the girl who had it all to come, his past self getting to live in the moment forever. That what was great about time, she was never gone, not really. Those moments were there, all of them, and she'd live them all out forever. And when she said that goodbye, with that smile of hers and the way she turned her body and run up the stairs- it was so very her. An adventure, her whole life just an adventure.
If he could die from heartbreak he would've already, the radiation was doing it on him but his hearts were already dead. They'd been dead for years, only beating for a few fleeting hours he got to hold her again before watching her run off with a man who looked exactly like him. That wasn't fair.
That was life though, his life. The sacrifices he had made to save the worlds and the universes every time. He always lost something in the end. And dear how he hated endings. He tried to express it to the air around him, the air that once held every breath of his favorite people in the world- even Jackie Tyler, but especially her daughter.
He whispered it to no one, maybe to a blonde girl he wished was there like last time, but wasn't. Maybe to a redhead who was too witty for words and burned out her brain, or maybe a medical student who deserved to be the Doctor here. But he didn't want to go. No, Rose I don't want to go. Rose, I don't want to go.